Changes to pfctl to allow easier integration into a library

[Adrian Chadd]

[snip]

hi,

I'm looking at this, because I'm thinking of what it'd take to make
some of this stuff in a daemon and be persistent, versus having to
fork/exec commands in a memory constrained environment.

Some static vars are effectively consts and are consts. Those may just
be committed as-is to make things clearer.

Some are actual state, which means I can't run this in a
multi-threaded environment.. :)



-adrian